Quantifying biological carbon export for the northwest North Atlantic continental shelves

Abstract

It has been suggested that continental shelf systems contribute disproportionately to the oceanic uptake of atmospheric CO2, but the magnitude of this flux and the relative contributions of different underlying mechanisms are poorly quantified. A biological continental shelf pump mechanism has been implied; however, the magnitude of this export depends on advective transport of carbon‐rich water off the shelf, a process that is difficult to observe directly. Here we use a physical‐biogeochemical model for the northeastern North American continental margin to estimate the uptake of atmospheric CO2, the fraction of this uptake that results from biological processes, and the transport of organic carbon off the shelf. Our results suggest that there is no systematic difference in the area‐normalized CO2 uptake between the shelf regions and the adjacent deep ocean. The advective transport of carbon‐rich water off the shelf is insufficient to drive a Continental Shelf Pump in this region.